Most of what a devops person does is in fact development but it is of the non value adding variety. Basically a devops person spends the vast majority of their time configuring common off the shelf software, scripting this or that, etc.
A singular matrix is a matrix which has no inverse because its determinant is zero. If you recall, the inverse of a matrix is. 1/ ad-bc multiplied by: [ d -b ] [-c a ] If ad-bc = 0, then the inverse matrix would not exist because 1/0 is undefined, and hence it would be a singular matrix. E.g.
Definition of matrix for English Language Learners. : 1  something (such as a situation or a set of conditions) in which something else develops or forms. : 2  something shaped like a pattern of lines and spaces. : 3  a container that can be filled with a material (such as very hot metal) to give the material a new shape.